TLC320AC02C Datasheet, PDF (32/84 Pages) Texas Instruments – Single-Supply Analog Interface Circuit

2.17 Request for Secondary Serial Communication and Phase Shift
The following paragraphs describe a request for secondary serial communication and phase shift using
hardware control inputs FC1 and FC0, primary data bits D01 and D00, and secondary data bits DS15 and
DS14.
2.17.1 Initiating a Request
Combinations of FC1 and FC0 input conditions, bits D01 and D00 in the primary serial data word, FC1 and
FC0, and bits DS15 and DS14 in the secondary serial data word can initiate a secondary serial
communication or request a phase shift according to the following rules (see Table 2–3).
1. Primary word phase shifts can be requested by either the hardware or software when the other
set of signals are 11 or 00. If both hardware and software request phase shifts, the software
request is performed.
2. Secondary words can be requested by either the software or hardware at the same time that the
other set of signals is requesting a phase shift.
3. Hardware inputs FC1 and FC0 are ignored during the secondary word unless DS15 and DS14
are 11. When DS15 and DS14 are 01 or 10, the corresponding phase shift is performed. When
DS15 and DS14 are 00, no phase shift is performed even when the hardware requests a phase
shift.
2.17.2 Normal Combinations of Control
The normal combinations of control are as follows:
1. Use D01 and D00 and DS15 and DS14 to request phase shifts and secondary words by holding
FC1 and FC0 to 00.
2. Use FC1 and FC0 exclusively to request phase shifts and secondary words by holding D01 and
D00 to 00 and DS15 and DS14 to 11.
3. Use D01 and D00 only to request secondary words and FC1 and FC0 to perform phase shifts
once per period by holding DS15 and DS14 to 00.
2.17.3 Additional Control Options
Additional control options are unusual and are rarely needed or used; however, they are as follows:
1. Use D01 and D00 only to request secondary words and FC1 and FC0 to perform phase shifts
twice per period by holding DS15 and DS14 to 11.
2. Use FC1 and FC0 exclusively to request secondary words and D01 and D00 and DS15 and DS14
to perform phase shifts twice per period.
3. Use FC1 and FC0 to perform the phase shift after the primary word and DS15 and DS14 to
perform a phase shift after the secondary word by holding D01 and D00 to 11.
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